linux-kernel - [RFC PATCH 5/6] cxl: Use __free() for cxl_pci/mem_find_port() to drop put

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Message-Id: <20240313083602.239201-6-ming4.li@intel.com>
Date: Wed, 13 Mar 2024 08:36:01 +0000
From: Li Ming <ming4.li@...el.com>
To: dan.j.williams@...el.com,
	rrichter@....com,
	terry.bowman@....com
Cc: linux-cxl@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Li Ming <ming4.li@...el.com>
Subject: [RFC PATCH 5/6] cxl: Use __free() for cxl_pci/mem_find_port() to drop put_device()

Introduce a new helper function called put_cxl_port() to instead of the
put_device() in order to release the device reference of struct cxl_port
got via get_device() in cxl_pci/mem_find_port().

Besides, use scope-based resource management __free() to drop the open
coded put_device() for each cxl_pci/mem_find_port().

Suggested-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Li Ming <ming4.li@...el.com>
---
 drivers/cxl/core/pci.c  |  6 ++----
 drivers/cxl/core/port.c |  9 +++++++++
 drivers/cxl/cxl.h       |  2 ++
 drivers/cxl/mem.c       |  5 ++---
 drivers/cxl/pci.c       | 12 +++++-------
 5 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 6c9c8d92f8f7..7254484330d2 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -902,15 +902,13 @@ static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
 	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
 	struct aer_capability_regs aer_regs;
 	struct cxl_dport *dport;
-	struct cxl_port *port;
 	int severity;
+	struct cxl_port *port __free(put_cxl_port) =
+		cxl_pci_find_port(pdev, &dport);
 
-	port = cxl_pci_find_port(pdev, &dport);
 	if (!port)
 		return;
 
-	put_device(&port->dev);
-
 	if (!cxl_rch_get_aer_info(dport->regs.dport_aer, &aer_regs))
 		return;
 
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index e59d9d37aa65..6e2fc2fce7c9 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1671,6 +1671,15 @@ struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd,
 }
 EXPORT_SYMBOL_NS_GPL(cxl_mem_find_port, CXL);
 
+void put_cxl_port(struct cxl_port *port)
+{
+	if (!port)
+		return;
+
+	put_device(&port->dev);
+}
+EXPORT_SYMBOL_NS_GPL(put_cxl_port, CXL);
+
 static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
 				    struct cxl_port *port, int *target_map)
 {
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index b6017c0c57b4..476158782e3e 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -743,6 +743,8 @@ struct cxl_port *cxl_pci_find_port(struct pci_dev *pdev,
 				   struct cxl_dport **dport);
 struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd,
 				   struct cxl_dport **dport);
+void put_cxl_port(struct cxl_port *port);
+DEFINE_FREE(put_cxl_port, struct cxl_port *, if (_T) put_cxl_port(_T))
 bool schedule_cxl_memdev_detach(struct cxl_memdev *cxlmd);
 
 struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port,
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index c5c9d8e0d88d..5aaa8ee2a46d 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -109,7 +109,6 @@ static int cxl_mem_probe(struct device *dev)
 	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	struct device *endpoint_parent;
-	struct cxl_port *parent_port;
 	struct cxl_dport *dport;
 	struct dentry *dentry;
 	int rc;
@@ -146,7 +145,8 @@ static int cxl_mem_probe(struct device *dev)
 	if (rc)
 		return rc;
 
-	parent_port = cxl_mem_find_port(cxlmd, &dport);
+	struct cxl_port *parent_port __free(put_cxl_port) =
+		cxl_mem_find_port(cxlmd, &dport);
 	if (!parent_port) {
 		dev_err(dev, "CXL port topology not found\n");
 		return -ENXIO;
@@ -170,7 +170,6 @@ static int cxl_mem_probe(struct device *dev)
 	rc = devm_cxl_add_endpoint(endpoint_parent, cxlmd, dport);
 unlock:
 	device_unlock(endpoint_parent);
-	put_device(&parent_port->dev);
 	if (rc)
 		return rc;
 
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 4fd1f207c84e..d0ec8c5b1e99 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -473,23 +473,21 @@ static bool is_cxl_restricted(struct pci_dev *pdev)
 static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
 				  struct cxl_register_map *map)
 {
-	struct cxl_port *port;
 	struct cxl_dport *dport;
 	resource_size_t component_reg_phys;
+	struct cxl_port *port __free(put_cxl_port) =
+		cxl_pci_find_port(pdev, &dport);
+
+	if (!port)
+		return -EPROBE_DEFER;
 
 	*map = (struct cxl_register_map) {
 		.host = &pdev->dev,
 		.resource = CXL_RESOURCE_NONE,
 	};
 
-	port = cxl_pci_find_port(pdev, &dport);
-	if (!port)
-		return -EPROBE_DEFER;
-
 	component_reg_phys = cxl_rcd_component_reg_phys(&pdev->dev, dport);
 
-	put_device(&port->dev);
-
 	if (component_reg_phys == CXL_RESOURCE_NONE)
 		return -ENXIO;
 
-- 
2.40.1